Cameroonian medicinal plants: pharmacology and derived natural products

Abstract

Many developing countries including Cameroon have mortality patterns that reflect high levels of infectious diseases and the risk of death during pregnancy and childbirth, in addition to cancers, cardiovascular diseases and chronic respiratory diseases that account for most deaths in the developed world. Several medicinal plants are used traditionally for their treatment. In this review, plants used in Cameroonian traditional medicine with evidence for the activities of their crude extracts and/or derived products have been discussed. A considerable number of plant extracts and isolated compounds possess significant antimicrobial, anti-parasitic including antimalarial, anti-proliferative, anti-inflammatory, anti-diabetes, and antioxidant effects. Most of the biologically active compounds belong to terpenoids, phenolics, and alkaloids. Terpenoids from Cameroonian plants showed best activities as anti-parasitic, but rather poor antimicrobial effects. The best antimicrobial, anti-proliferative, and antioxidant compounds were phenolics. In conclusion, many medicinal plants traditionally used in Cameroon to treat various ailments displayed good activities in vitro. This explains the endeavor of Cameroonian research institutes in drug discovery from indigenous medicinal plants. However, much work is still to be done to standardize methodologies and to study the mechanisms of action of isolated natural products.

Keywords: Africa; ethnopharmacology; medicinal plants.

Figure 1

Portion of land area protected (A) by IUCN Category (2003) and threatened species (B) (2002–2003) in Cameroon (Source: EarthTrends, 2003). IUCN, International Union for the Conservation of Nature and Natural Resources; Categories I, nature reserves, wilderness, areas; Categories II, national parks; Category III, natural monument; Category IV, habitat/species management area; Category V, protected landscape/seascape.

Figure 2

Bioactive terpenoids. Activity [(a) antimalarial, (b) anti-inflammatory, (c) antitrypanosomal]; Glc, glucosyl group; Ac, acetyl group.

Figure 3

Bioactive phenolics [quinones (23–29), xanthones (30–42), arylbenzofurans (43–46)]. Activity [(a) antimicrobial, (b) anti-inflammatory, (c) antimalarial, (d) anti-proliferative, (e) antioxidant]. [Chalcones (47–49), benzophenone (50), flavone (51–52), isoflavones (53–56), pterocarpene (57), ellagic acid derivative (58)]. Activity [(a) antimicrobial, (b) anti-inflammatory, (c) antimalarial, (d) anti-proliferative, (e) antioxidant].

Figure 4

Bioactive alkaloids. Activity [(a) antimicrobial, (b) antimalarial, (c) antileishmanial].